Using satellite imagery, researchers have found that subnival vegetation, the vegetation that grows between the treeline and snowline, is increasing in spatial extent around the Mount Everest and Himalaya area. The subnival zone in the Hindu Kush Himalayan (HKH) region (known as ‘The Third Pole”) is poorly studied due to its high altitude and subsequent inaccessibility. The research looked at two questions: what is the extent of the subnival zone and how and where has the rate of change occurred in the spatial extent? To do this, researchers from the University of Exeter analyzed Landsat imagery from 1993 to 2018 using NDVI analysis (which measures vegetation cover based on surface reflectance) to look at subnival vegetation cover at four elevation brackets between 4,150 and 6,000 meters above sea level. The researchers found that there was “a weakly positive increase in the extent of subnival vegetation.” This trend was strongest among plant cover at the 5,000 to 5,500 meter elevations. They also found that trends in plant cover increase were stronger at lower elevations on steep slopes and on flatter terrain at higher elevations. The research only looked at the change from bare or sparsely covered ground to vegetated ground. The NDVI classification did not address any changes in species composition within the subnival ecosystem.
The study:
Anderson, K., Fawcett, D., Cugulliere, A., Benford, S., Jones, D., & Leng, R. (2020). Vegetation expansion in the subnival Hindu Kush Himalaya. Global Change Biology, 2019; 00: 1– 18. https://doi.org/10.1111/gcb.14919
Plant life expanding in the Everest region. University of Exeter. January 10, 2020.
